One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10)(11,16)(12,15)(13,14)(19,23)(21,24)(25,26)(27,30)(28,31)(29,32)(33,35)(34,38)(36,37)(39,40) involution — undirected(2,4)(3,8)(9,11)(10,15)(12,14)(13,16)(25,26,29,32)(27,30,35,33)(28,36,37,31)(34,39,40,38)(1,2,5,4)(3,7,8,6)(9,10,14,13)(11,15,12,16)(17,18,20,22)(19,21,23,24)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,37)(38,40)(1,3,5,8)(2,6,4,7)(9,12,14,11)(10,15,13,16)(17,19,20,23)(18,21,22,24)(25,27,29,35)(26,30,32,33)(28,34,37,40)(31,38,36,39)(1,4,5,2)(3,7,8,6)(9,13,14,10)(11,15,12,16)(25,28,29,37)(26,31,32,36)(27,34,35,40)(30,38,33,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.